Aromatic resins for underlayers

ABSTRACT

Polymeric reaction products of certain aromatic alcohols with certain aromatic aldehydes are useful as underlayers in semiconductor manufacturing processes.

The present invention relates generally to field of manufacturing electronic devices, and more specifically to the field of materials for use in semiconductor manufacture.

It is well-known in lithographic processes that a resist pattern can collapse due to surface tension from the developer used if the resist pattern is too tall (high aspect ratio). Multilayer resist processes (such as three- and four-layer processes) have been devised which can address this issue of pattern collapse where a high aspect ratio is desired. Such multilayer processes use a resist top layer, one or more middle layers, and a bottom layer (or underlayer). In such multilayer resist processes, the top photoresist layer is imaged and developed in typical fashion to provide a resist pattern. The pattern is then transferred to the one or more middle layers, typically by etching. Each middle layer is selected such that a different etch process is used, such as different plasma etches. Finally, the pattern is transferred to the underlayer, typically by etching. Such middle layers may be composed of various materials while the underlayer materials are typically composed of high carbon content materials. The underlayer material is selected to provide desired antireflective properties, planarizing properties, as well as etch selectivity.

Many attempts have been made to develop underlayer materials which possess desired antireflective properties and etch selectivity, and which are suitable for use with these multilayer processes. One feature of etch selectivity is the etch resistance of an organic material to plasma etches. It is generally desired in the industry to develop underlayer materials that have improved etch resistance as compared to conventional materials. Korean Pat. App. No. 2010080139 A discloses certain aromatic polymers formed from the self-condensation of pyrenol compounds in toluene (a non-polar solvent). Such aromatic polymers do not show desired etch selectivity, that is, etch resistance. U.S. Published Pat. App. No. 2010/0021830 discloses certain pyrene-containing aromatic polymers, but does not disclose polymers having certain fused aromatic ring moieties pendant from the polymer backbone. There remains a need for underlayer materials that possess desired antireflective properties and improved etch selectivity, particularly improved etch resistance to O₂ and CF₄ plasmas.

The present invention provides a reaction product formed from a combination comprising one or more first monomers of the formula (I)

wherein Y is selected from H, C₁-C₃₀alkyl, C₂-C₃₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —C₁-C₃₀alkylene-OR¹, and —C₁-C₃₀alkylidene-OR¹; each R is independently selected from C₁-C₃₀alkyl, C₂-C₃₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —OR¹, —C₁-C₃₀alkylene-OR¹, and —C₁-C₃₀alkylidene-OR¹; R¹ is selected from H, C₁-C₃₀alkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, and C₇-C₃₀aralkyl; and n is an integer selected from 0 to 7; and one or more second monomers of the formula Ar—CHO, where Ar is a C₁₀-C₃₀aromatic moiety having at least 2 fused aromatic rings, which may optionally be substituted with one or more of C₁-C₃₀alkyl, C₂-C₃₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —OR³, —C₁-C₃₀alkylene-OR³ and —C₁-C₃₀alkylidene-OR³; R³ is selected from H, C₁-C₃₀alkyl, and C₆-C₃₀aryl.

Also provided by the present invention is a process for preparing the reaction product described above comprising reacting one or more first monomers of the formula (I)

wherein Y is selected from H, C₁-C₃₀alkyl, C₂-C₃₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —C₁-C₃₀alkylene-OR¹, and —C₁-C₃₀alkylidene-OR¹; each R is independently selected from C₁-C₃₀alkyl, C₂-C₃₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —OR¹, —C₁-C₃₀alkylene-OR¹, and —C₁-C₃₀alkylidene-OR¹; R¹ is selected from H, C₁-C₃₀alkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, and C₇-C₃₀aralkyl; and n is an integer selected from 0 to 7; with one or more second monomers of the formula Ar—CHO, where Ar is a C₁₀-C₃₀aromatic moiety having at least 2 fused aromatic rings, which may optionally be substituted with one or more of C₁-C₃₀alkyl, C₂-C₃₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —OR³, —C₁-C₃₀alkylene-OR³ and —C₁-C₃₀alkylidene-OR³; R³ is selected from H, C₁-C₃₀alkyl, and C₆-C₃₀aryl in the presence of an acid, and optionally in a solvent. The present invention also provides a reaction product produced by the process described above.

Further, the present invention provides a composition comprising the reaction product described above, organic solvent, and optionally one or more additives chosen from curing agents, crosslinking agents, and surfactants.

The present invention also provides a process of forming a patterned layer comprising disposing a layer of the composition described above on a substrate; removing organic solvent to form a reaction product layer; disposing a layer of a photoresist on the polymeric reaction product layer; exposing the photoresist layer to actinic radiation through a mask; developing the exposed photoresist layer to form a resist pattern; and transferring the pattern to the reaction product layer to expose portions of the substrate.

It will be understood that when an element is referred to as being “on” another element, it can be directly adjacent to the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

It will be understood that although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.

As used throughout this specification, the following abbreviations shall have the following meanings, unless the context clearly indicates otherwise: ° C.=degree Celsius; g=gram; mg=milligram; ppm=part per million; μm=micron=micrometer; nm=nanometer; A=angstrom; L=liter; and mL=milliliter. All amounts are percent by weight and all ratios are molar ratios, unless otherwise noted. All numerical ranges are inclusive and combinable in any order, except where it is clear that such numerical ranges are constrained to add up to 100%. “Wt %” refers to percent by weight, based on the total weight of a referenced composition, unless otherwise noted.

As used throughout the specification, “feature” refers to the geometries on a substrate, and particularly on a semiconductive wafer. The term “alkyl” includes linear, branched and cyclic alkyl. Likewise, “alkenyl” refers to linear, branched and cyclic alkenyl. By the term “curing” is meant any process, such as polymerization or condensation, that increases the molecular weight of a material or composition. “Curable” refers to any material capable of being cured under certain conditions. The term “oligomer” refers to dimers, trimers, tetramers and other relatively low molecular weight materials that are capable of further curing. The articles “a”, “an” and “the” refer to the singular and the plural.

“Aryl” refers to aromatic carbocycles and aromatic heterocycles, and preferably aromatic carbocycles. As used herein, the term “substituted” aryl refers to any aryl moiety having one or more of its hydrogens replaced with one or more substituents selected from C₁-C₃₀alkyl, C₂-C₃₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, —OR³, —C₁-C₃₀alkylene-OR³, and —C₁-C₃₀alkylidene-OR³; R³ is selected from H, C₁-C₃₀alkyl, and C₆-C₃₀aryl. Preferably, “substituted” aryl refers to any aryl moiety having one or more of its hydrogens replaced with one or more substituents selected from C₁-C₂₀alkyl, C₂-C₂₀alkenyl, C₇-C₃₀aralkyl, C₆-C₂₀aryl, —OR³, —C₁-C₂₀alkylene-OR³, and —C₁-C₂₀alkylidene-OR³; and more preferably from C₁-C₁₀alkyl, C₂-C₁₂alkenyl, C₇-C₃₀aralkyl, C₆-C₂₀aryl, —OR³, —C₁-C₂₀alkylene-OR³, and —C₁-C₂₀alkylidene-OR³. Preferably, R³ is selected from H, C₁-C₂₀alkyl, and C₆-C₂₀aryl, and more preferably H, C₁-C₁₀alkyl, and C₆-C₂₀aryl.

Reaction products of the invention are aromatic resins that are particularly suitable for use as underlayers in a variety of electronic device manufacturing processes. Such reaction products also have good gap filling properties. The aromatic resins of the invention are reactions products of at least one or more first monomers, each of which is a pyrenol compound, and one or more second monomers, each of which is an aromatic aldehyde having at least 2 fused aromatic rings.

The pyrenol compounds useful as the first monomer have the formula (I):

wherein Y is selected from H, C₁-C₃₀alkyl, C₂-C₃₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —C₁-C₃₀alkylene-OR¹, and —C₁-C₃₀alkylidene-OR¹; each R is independently selected from C₁-C₃₀alkyl, C₂-C₃₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —OR¹, —C₁-C₃₀alkylene-OR¹, and —C₁-C₃₀alkylidene-OR¹; R¹ is selected from H, C₁-C₃₀alkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, and C₇-C₃₀aralkyl; and n is an integer selected from 0 to 7. Preferably, Y is chosen from H, C₁-C₂₀alkyl, C₂-C₂₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —C₁-C₁₂alkylene-OR¹, and —C₁-C₂₀alkylidene-OR¹; more preferably H, C₁-C₁₆alkyl, C₂-C₁₆alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —C₁-C₁₀alkylene-OR¹, and —C₁-C₂₀alkylidene-OR¹; yet more preferably H, C₁-C₁₀alkyl, C₂-C₁₂alkenyl, C₇-C₃₀aralkyl, C₆-C₂₀aryl, substituted C₆-C₂₀aryl, —C₁-C₁₂alkylene-OR¹, and —C₁-C₁₂alkylidene-OR¹, and even more preferably H. In the monomers of formula (I), any of the aromatic rings of the pyrenol moiety may be substituted with one or more R groups. It is preferred that n is an integer from 0 to 5, more preferably from 0 to 4, and even more preferably from 0 to 3. Preferably, each R is independently selected from C₁-C₂₀alkyl, C₂-C₂₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —OR¹, —C₁-C₁₂alkylene-OR¹, and —C₁-C₂₀alkylidene-OR¹; more preferably C₁-C₁₆alkyl, C₂-C₁₆alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —OR¹, —C₁-C₁₀alkylene-OR¹, and —C₁-C₂₀alkylidene-OR¹; and yet more preferably C₁-C₁₀alkyl, C₂-C₁₂alkenyl, C₇-C₃₀aralkyl, C₆-C₂₀aryl, substituted C₆-C₂₀aryl, —OR¹, —C₁-C₁₂alkylene-OR¹, and —C₁-C₁₂alkylidene-OR¹. It is particularly preferred that each R is independently selected from C₁-C₁₀alkyl, C₂-C₁₂alkenyl, C₇-C₃₀aralkyl, C₆-C₂₀aryl, substituted C₆-C₂₀aryl, OH, C₁-C₆alkoxy, and —C₁-C₁₀alkylene-OR¹. Preferably, R¹ is selected from H, C₁-C₂₀alkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, and C₇-C₃₀aralkyl; more preferably from H, C₁-C₁₆alkyl, C₆-C₂₀aryl, substituted C₆-C₂₀aryl, and C₇-C₃₀aralkyl; and yet more preferably from H, C₁-C₁₀alkyl, C₆-C₂₀aryl, substituted C₆-C₂₀aryl, and C₇-C₃₀aralkyl. Mixtures of first monomer may be used.

Exemplary substituents suitable as R groups in formula (I) are, without limitation, hydroxyl, methyl, ethyl, propyl, iso-butyl, tert-butyl, cyclopentyl, cyclohexyl, cyclopentenylmethyl, cyclohexenylmethyl, 2-cyclohexenylmeth-1-yl, methoxy, ethoxy, propyloxy, phenyl, tolyl, xylyl, naphthyl, biphenyl, benzyl, phenethyl, naphthylmethyl, pyerenylmethyl, antracenylmethyl, methoxy, ethoxy, propyloxy, phenyloxy, naphthyloxy, benzyloxy, phenethyloxy, methoxymethyl, methoxyethyl, methoxyphenyl, and methoxynaphthyl.

The aromatic aldehyde useful as the second monomer has the formula Ar—CHO, where Ar is a C₁₀-C₃₀aromatic moiety having at least 2 fused aromatic rings, which may optionally be substituted with one or more of C₁-C₃₀alkyl, C₂-C₃₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —OR², —C₁-C₃₀alkylene-OR³, and —C₁-C₃₀alkylidene-OR³; R³ is selected from H, C₁-C₃₀alkyl, and C₆-C₃₀aryl. Preferably, Ar is a C₁₀-C₃₀aromatic moiety having from 2 to 5 fused aromatic rings, more preferably from 2 to 4 fused aromatic rings, and yet more preferably Ar is naphthyl. It is preferred that the C₁₀-C₃₀aromatic moiety of Ar is unsubstituted or substituted with one or more hydroxyls. Preferably, the aromatic aldehydes useful as the second monomer have the formula (IIa) or (IIb)

wherein A represents 1 to 4 fused aromatic rings; A1 represents 1 to 3 fused aromatic rings; each of A2 and A3 may be present or absent and each of A2 and A3 represents 1 to 2 fused aromatic rings; each R² is independently selected from C₁-C₃₀alkyl, C₂-C₃₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —OR³, —C₁-C₃₀alkylene-OR³; each R³ is selected from H, C₁-C₃₀alkyl, and C₆-C₃₀aryl; and m is an integer from 0 to 13; wherein A1, A2 and A3 represent a total of 3 fused aromatic rings. It is preferred that A represents 1 to 3 aromatic rings, and more preferably 1 to 2 fused aromatic rings, and most preferably 1 fused aromatic ring. Preferably, A1 represents 1 or 2 fused aromatic rings. More preferably, each of A1 and A3 represent 1 fused aromatic ring. In another preferred aromatic aldehyde, each of A1, A2 and A3 represent 1 fused aromatic ring. Preferably, each R² is independently selected from C₁-C₂₀alkyl, C₂-C₂₀alkenyl, C₇-C₃₀aralkyl, C₆-C₂₀aryl, —OR³, —C₁-C₂₀alkylene-OR³, and —C₁-C₂₀alkylidene-OR³; and more preferably from C₁-C₁₀alkyl, C₂-C₁₂alkenyl, C₇-C₃₀aralkyl, C₆-C₂₀aryl, —OR³, —C₁-C₂₀alkylene-OR³, and —C₁-C₂₀alkylidene-OR³. Preferably, R³ is selected from H, C₁-C₂₀alkyl, and C₆-C₂₀aryl, and more preferably H, C₁-C₁₀alkyl, and C₆-C₂₀aryl. Preferably, m is an integer from 0 to 10, more preferably from 0 to 8, still more preferably from 0 to 6, and yet more preferably from 0 to 5. Any of the fused aromatic rings in the structures of formulae (IIa) and (IIb) may be substituted with —CHO and/or one or more R² moieties, and at least one of the fused aromatic rings in the structures of formulae (IIa) and (IIb) is substituted with —CHO. Mixtures of second monomers may be used.

The present reaction products are prepared by reacting one or more first monomers of formula (I) described above with one or more aromatic aldehydes of the formula Ar—CHO described above, in the presence of an acid catalyst, and optionally in a suitable solvent. The monomers and optional solvent may be combined in any order. Acid catalyst is typically added to the reaction mixture after the monomers and any optional solvent. Preferably, the reaction mixture is heated, such as from room temperature to 50° C. before addition of the acid catalyst. Following addition of the acid catalyst, the reaction mixture is typically heated, such as at reflux, for a period of time, such as from 1 to 48 hours. Following heating, the reaction product is isolated from the reaction mixture, such as by precipitation, and is typically dried, and optionally purified, before use. The molar ratio of total first monomer to total second monomer is from 1:0.75 to 2:1, and preferably from 1:1 to 1.5:1.

Reaction products of the invention may be prepared by the one or more first monomers and one or more second monomers without a solvent (neat) or preferably in the presence of a solvent. A variety of solvents may be used to prepare the present aromatic resin reaction products, such as, but not limited to, alcohols, glycol ethers, lactones, esters, water, and aromatic hydrocarbons. Preferably, a relatively polar solvent is used, such as alcohols, glycol ethers, lactones, esters or water. Mixtures of solvents may be used. It is preferred that at least one relatively polar solvent be used in the solvent mixture. Exemplary solvents include, without limitation, methanol, ethanol, propanol, propylene glycol, propylene glycol methyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol methyl ether acetate (PGMEA), gamma-butyrolactone (GBL), gamma-valerolactone, delta-valerolactone, ethyl lactate, water, mesitylene, xylene, anisole, 4-methylanisole, and the like. Preferred solvents are methanol, ethanol, propanol, propylene glycol, propylene glycol methyl ether, propylene glycol dimethyl ether, propylene glycol methyl ether acetate, gamma-butyrolactone, gamma-valerolactone, delta-valerolactone, ethyl lactate, and water.

A variety of acids may suitably be used as catalysts in the preparation of the present aromatic resin reaction products. Such acids typically have a pKa of ≦2, preferably ≦1.5, more preferably ≦1, and yet more preferably ≦0. Exemplary acids include, without limitation, organic carboxylic acids and dicarboxylic acids such as propionic acid and oxalic acid, mineral acids and sulfonic acids, and preferably the acid catalysts is a mineral acid or a sulfonic acid. Suitable mineral acids are HF, HCl, HBr, HNO₃, H₂SO₄, H₃PO₄, and HClO₄. Suitable sulfonic acids include alkanesulfonic acids and arylsulfonic acids, such as methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, phenylsulfonic acid, phenolsulfonic acid, para-toluenesulfonic acid, and cresolsulfonic acid. Preferred acid catalysts are HCl, HBr, HNO₃, H₂SO₄, H₃PO₄, methanesulfonic acid, ethanesulfonic acid, phenylsulfonic acid, phenolsulfonic acid, and para-toluenesulfonic acid (pTSA).

The aromatic resin reaction products of the invention typically have a weight average molecular weight (M_(w)) of 500 to 20000, preferably from 500 to 15000, and more preferably from 500 to 10000, as determined by gel permeation chromatography (GPC) using polystyrene standards.

When the first and second monomers described above are reacted in a relatively polar solvent, such as a mixture of propylene glycol methyl ether (PGME), ethanol and water, with a mineral acid, such as HCl, as the acid catalyst, the resulting aromatic resin reaction product possess a relatively polar moiety which is not present in the same reaction product prepared using a relatively non-polar solvent, such as an aromatic hydrocarbon. Such relatively polar moiety can be detected by HPLC (using an Agilent Zorbax Eclipse XDB-C8 column, liquid phase: 90/10 DI water/acetonitrile, followed by tetrahydrofuran) equipped with an evaporative light scattering detector. Such aromatic resin reaction products having such a relatively polar moiety show improved etch selectivity (that is, etch resistance) compared to the same reaction product prepared using a relatively non-polar solvent, such as an aromatic hydrocarbon.

A suitable composition useful for forming an underlayer comprises one or more aromatic resin reaction products described above, organic solvent, and optionally one or more additives chosen from curing agents, crosslinking agents, and surfactants. Mixtures of the present aromatic resin reaction products may be used in the present compositions. It will be appreciated by those skilled in the art that other additives may suitably be used in the present compositions. Any solvent may be used, provided that a sufficient amount of the aromatic resin reaction product is soluble in solvent, or solvent mixture, used. Such solvents include, but are not limited to, aromatic hydrocarbons, alcohols, lactones, esters, glycols, and glycol ethers. Mixtures of organic solvents may be used. Exemplary organic solvents include, without limitation, toluene, xylene, mesitylene, 2-methyl-1-butanol, 4-methyl-2-pentanol, methyl isobutyl carbinol, gamma-butyrolactone, ethyl lactate, methyl 2-hydroxyisobutyrate propylene glycol methyl ether acetate, propylene glycol methyl ether, and cyclohexanone. It will be appreciated by those skilled in the art that the concentration of the aromatic resin reaction products in the solvent may be varied across a wide range and that the thickness of any film deposited by a spin-on technique depends on the concentration of the reaction products in the solvent. Typically, the amount of aromatic resin in the composition is from 5 to 20 wt %, based on the total weight of the composition.

Optionally, the present aromatic resin compositions may further comprise one or more curing agents to aid in the curing of the deposited aromatic resin film. A curing agent is any component which causes curing of the aromatic resin film on the surface of a substrate. Preferred curing agents are thermal acid generators. A thermal acid generator is any compound which liberates acid upon exposure to heat. Thermal acid generators are well-known in the art and are generally commercially available, such as from King Industries, Norwalk, Conn. Exemplary thermal acid generators include, without limitation, amine blocked strong acids, such as amine blocked sulfonic acids such as amine blocked dodecylbenzenesulfonic acid. It will also be appreciated by those skilled in the art that certain photoacid generators are able to liberate acid upon heating and may function as thermal acid generators. The amount of such curing agents useful in the present compositions is well-known to those skilled in the art and is typically from 0 to 10 wt %, and preferably from 0 to 3 wt %.

Any suitable crosslinking agent may be used in the present compositions, provided that such crosslinking agent has at least 2, and preferably at least 3, moieties capable of reacting with the present aromatic resin reaction products under suitable conditions, such as under acidic conditions. Exemplary crosslinking agents include, but are not limited to, novolac resins, epoxy-containing compounds, melamine compounds, guanamine compounds, isocyanate-containing compounds, benzocyclobutenes, and the like, and preferably any of the foregoing having 2 or more, preferably 3 or more, and more preferably 4, substituents selected from methylol, C₁-C₁₀alkoxymethyl, and C₂-C₁₀acyloxymethyl. Examples of suitable crosslinking agents are those shown by formulae (III) and (IV).

Such crosslinking agents are well-known in the art, and are commercially available from a variety of sources. The amount of such crosslinking agents useful in the present compositions is well-known to those skilled in the art, and typically is in the range of 0 to 30 wt %, and preferably from 0 to 10 wt %.

The present aromatic resin compositions may optionally include one or more surface leveling agents (or surfactants). While any suitable surfactant may be used, such surfactants are typically non-ionic. Exemplary non-ionic surfactants are those containing an alkyleneoxy linkage, such as ethyleneoxy, propyleneoxy, or a combination of ethyleneoxy and propyleneoxy linkages. The amount of such surfactants useful in the present compositions is well-known to those skilled in the art, and typically is in the range of 0 to 5 wt %.

The present aromatic resin reaction products are useful in the manufacture of various electronic devices, such as in a process of forming a patterned layer comprising disposing a layer of the composition described above on a substrate; removing organic solvent to form a reaction product layer; disposing a layer of a photoresist on the reaction product layer; exposing the photoresist layer to actinic radiation through a mask; developing the exposed photoresist layer to form a resist pattern; and transferring the pattern to the reaction product layer to expose portions of the substrate.

The present compositions may be disposed on an electronic device substrate by any suitable means, such as spin-coating, slot-die coating, doctor blading, curtain coating, roller coating, spray coating, dip coating, and the like. Spin-coating is preferred. In a typical spin-coating method, the present compositions are applied to a substrate which is spinning at a rate of 500 to 4000 rpm for a period of 15-90 seconds to obtain a desired layer of the aromatic resin reaction product on the substrate. It will be appreciated by those skilled in the art that the height of the aromatic resin layer may be adjusted by changing the spin speed.

A wide variety of electronic device substrates may be used in the present invention, such as: packaging substrates such as multichip modules; flat panel display substrates; integrated circuit substrates; substrates for light emitting diodes (LEDs) including organic light emitting diodes (OLEDs); semiconductor wafers; polycrystalline silicon substrates; and the like. Such substrates are typically composed of one or more of silicon, polysilicon, silicon oxide, silicon nitride, silicon oxynitride, silicon germanium, gallium arsenide, aluminum, sapphire, tungsten, titanium, titanium-tungsten, nickel, copper, and gold. Suitable substrates may be in the form of wafers such as those used in the manufacture of integrated circuits, optical sensors, flat panel displays, integrated optical circuits, and LEDs. As used herein, the term “semiconductor wafer” is intended to encompass “an electronic device substrate,” “a semiconductor substrate,” “a semiconductor device,” and various packages for various levels of interconnection, including a single-chip wafer, multiple-chip wafer, packages for various levels, or other assemblies requiring solder connections. Such substrates may be any suitable size. Preferred wafer substrate diameters are 200 mm to 300 mm, although wafers having smaller and larger diameters may be suitably employed according to the present invention. As used herein, the term “semiconductive substrates” includes any substrate having one or more semiconductor layers or structures which include active or operable portions of semiconductor devices. The term “semiconductor substrate” is defined to mean any construction comprising semiconductive material, including but not limited to bulk semiconductive material such as a semiconductive wafer, either alone or in assemblies comprising other materials thereon, and semiconductive material layers, either alone or in assemblies comprising other materials. A semiconductor device refers to a semiconductor substrate upon which at least one microelectronic device has been or is being batch fabricated.

After being deposited on the substrate, the aromatic resin underlayer is optionally baked at a relatively low temperature to remove any solvent and other relatively volatile components from the underlayer. Typically, the substrate is baked at a temperature of ≦150° C., preferably from 60 to 125° C., and more preferably from 90 to 115° C. The baking time is typically from 10 seconds to 10 minutes, preferably from 30 seconds to 5 minutes, and more preferably from 6 to 90 seconds. When the substrate is a wafer, such baking step may be performed by heating the wafer on a hot plate.

The aromatic resin underlayer is then sufficiently cured such that the film does not intermix with a subsequently applied organic layer, such as a photoresist or other organic layer disposed directly on the underlayer. The aromatic resin underlayer may be cured in an oxygen-containing atmosphere, such as air, or in an inert atmosphere, such as nitrogen and under conditions, such as heating, sufficient to provide a cured aromatic resin underlayer. Such conditions are sufficient to cure the film such that it does not intermix with a subsequently applied organic layer, such as a photoresist layer, while still maintaining the desired antireflective properties (n and k values) and etch selectivity of the underlayer film. This curing step is conducted preferably on a hot plate-style apparatus, though oven curing may be used to obtain equivalent results. Typically, such curing is performed by heating the aromatic resin layer at a curing temperature of ≧150° C., and preferably 150 to 450° C. It is more preferred that the curing temperature is ≧200° C., still more preferably ≧250° C., and even more preferably from 250 to 400° C. The curing temperature selected should be sufficient for any thermal acid generator used to liberate acid to aid in curing of the aromatic resin. The curing time may be from 10 seconds to 10 minutes, preferably from 30 seconds to 5 minutes, more preferably from 45 seconds to 5 minutes, and yet more preferably from 45 to 90 seconds. The choice of final curing temperature depends mainly upon the desired curing rate, with higher curing temperatures requiring shorter curing times.

The initial baking step may not be necessary if the curing step is conducted in such a way that rapid evolution of the solvents and curing by-products is not allowed to disrupt the film quality. For example, a ramped bake beginning at relatively low temperatures and then gradually increasing to the range of 200 to 325° C. can give acceptable results. It can be preferable in some cases to have a two-stage curing process, with the first stage being a lower bake temperature of less than 200° C., and the second stage being a higher bake temperature preferably between 200 and 400° C. Two stage curing processes facilitate uniform filling and planarization of pre-existing substrate surface topography, for example filling of trenches and vias.

After curing of the aromatic resin underlayer, one or more processing layers, such as photoresists, silicon-containing layers, hardmask layers, bottom antireflective coating (or BARC) layers, and the like, may be disposed on the cured underlayer. For example, a photoresist may be disposed, such as by spin coating, directly on the surface of the cured aromatic resin underlayer. A wide variety of photoresists may be suitably used, such as those used in 193 nm lithography, such as those sold under the EPIC™ brand available from Dow Electronic Materials (Marlborough, Mass.). Suitable photoresists may be either positive tone development or negative tone development resists. Following coating on the aromatic resin underlayer, the photoresist layer is then imaged (exposed) using patterned actinic radiation, and the exposed photoresist layer is then developed using the appropriate developer to provide a patterned photoresist layer. The pattern is next transferred from the photoresist layer to the underlayer by an appropriate etching technique. Typically, the photoresist is also removed during such etching step. Next, the pattern is transferred to the substrate and the underlayer removed by appropriate etching techniques known in the art, such as by plasma etching. Following patterning of the substrate, the underlayer is removed using conventional techniques. The electronic device substrate is then processed according to conventional means.

Alternatively, the cured aromatic resin underlayer may be used as the bottom layer of a multilayer resist process. In such a process, a layer of the aromatic resin reaction product is disposed on a substrate and cured as described above. Next, one or more middle layers are disposed on the aromatic resin underlayer. For example, a silicon-containing layer or a hardmask layer is disposed directly on the aromatic resin underlayer. Exemplary silicon-containing layers include a silicon-BARC, which may be spin coated on the underlayer followed by curing, or an inorganic silicon layer such as SiON or SiO₂ which may be deposited on the underlayer by chemical vapor deposition (CVD). Any suitable hardmask may be used and may be deposited on the underlayer by any suitable technique, and cured as appropriate. Optionally, an organic BARC layer may be disposed directly on the silicon-containing layer or hardmask layer, and appropriately cured. Next, a photoresist, such as those used in 193 nm lithography, is disposed directly on the silicon-containing layer (in a trilayer process) or directly on the organic BARC layer (in a quadlayer process). The photoresist layer is then imaged (exposed) using patterned actinic radiation, and the exposed photoresist layer is then developed using the appropriate developer to provide a patterned photoresist layer. The pattern is next transferred from the photoresist layer to the layer directly below it, by appropriate etching techniques known in the art, such as by plasma etching, resulting in a patterned silicon-containing layer in a trilayer process and a patterned organic BARC layer in a quadlayer process. If a quadlayer process is used, the pattern is next transferred from the organic BARC layer to the silicon-containing layer or hardmask layer using appropriate pattern transfer techniques, such as plasma etching. After the silicon-containing layer or hardmask layer is patterned, the aromatic resin underlayer is then patterned using appropriate etching techniques, such as O₂ plasma. Any remaining patterned photoresist and organic BARC layers are removed during etching of the aromatic resin underlayer. Next, the pattern is then transferred to the substrate, such as by appropriate etching techniques, which also removes any remaining silicon-containing layer or hardmask layer, followed by removal of any remaining patterned aromatic resin underlayer to provide a patterned substrate.

Aromatic reaction products of the invention may also be used in a self-aligned double patterning process. In such a process, a layer of an aromatic resin reaction product described above is disposed on a substrate, such as by spin-coating. Any remaining organic is removed and the aromatic resin layer is cured to form an aromatic resin underlayer. A layer of a suitable photoresist is then disposed on the cured aromatic resin underlayer, such as by spin coating. The photoresist layer is then imaged (exposed) using patterned actinic radiation, and the exposed photoresist layer is then developed using the appropriate developer to provide a patterned photoresist layer. The pattern is next transferred from the photoresist layer to the aromatic resin underlayer by an appropriate etching technique to expose portions of the substrate. Typically, the photoresist is also removed during such etching step. Next, a conformal silicon-containing layer is disposed over the patterned polymeric reaction product layer and exposed portions of the substrate. Such silicon-containing layer is typically an inorganic silicon layer such as SiON or SiO₂ which is conventionally deposited by CVD. Such conformal coatings result in a silicon-containing layer on the exposed portions of the substrate surface as well as over the underlayer pattern, that is, such silicon-containing layer substantially covers the sides and top of the underlayer pattern. Next, the silicon-containing layer is partially etched (trimmed) to expose a top surface of the patterned aromatic resin underlayer and a portion of the substrate. Following this partial etching step, the pattern on the substrate comprises a plurality of features, each feature comprising a line or post of the aromatic resin underlayer with the silicon-containing layer directly adjacent to the sides of each aromatic resin underlayer feature. Next, the aromatic resin underlayer is removed, such as by etching, to expose the substrate surface that was under the aromatic resin underlayer pattern, and providing a patterned silicon-containing layer on the substrate surface, where such patterned silicon-containing layer is doubled (that is, twice as many lines and/or posts) as compared to the patterned aromatic resin underlayer.

The present aromatic resin reaction products provide underlayers having improved etch resistance to oxygen and fluorine gases, high carbon content, reduced or no swelling from exposure to processing fluids, and very good planarization and gap filling properties, making such reaction products useful in a variety of semiconductor manufacturing processes.

EXAMPLE 1

A three-necked 50 mL round-bottom flask was equipped with a mechanical stirrer, a thermowell, and a condenser with a nitrogen inlet. The flask was charged with 1-pyrenol (5.0 g, 0.0229 mol), 2-naphthaldehyde (3.578 g, 0.0229 mol), and PGME (10 mL) and EtOH (7 mL). Stirring was then initiated and the reaction mixture was heated to 60° C. under nitrogen. A clear solution was obtained after 30 minutes and heating was removed at that time. HCl (3.0 mL, 37% in water) was added dropwise to the reaction mixture at 40° C. The reaction mixture was refluxed for 24 hours to give a thick, dark brown solution. The reaction mixture was cooled to room temperature and diluted with 10 mL PGME. The mixture was then added to 250 mL methanol to give a light grey precipitate. The precipitated resin was filtered, vacuum dried at 60 to 70° C. to give 4.3 g resin (Sample 1) as grey powder. Analysis by GPC: M_(w)=2321, polydispersity index (PDI)=1.24.

EXAMPLE 2

The procedure of Example 1 was repeated and analysis of the resulting resin (Sample 2) by GPC provided the following: M_(w)=2231, PDI=1.33.

EXAMPLE 3

A three-necked 50 mL round-bottom flask was equipped with a mechanical stirrer, a thermowell, and a condenser with a nitrogen inlet. The flask was charged with 1-pyrenol (4.0 g, 0.0183 mol), 2-naphthaldehyde (2.8624 g, 0.0183 mol), and toluene (24 mL). Stirring was then initiated and the reaction mixture was heated to 60° C. under nitrogen. A clear solution was obtained after 30 minutes and heating was removed at that time. Methanesulfonic acid (1.76 g, 0.0183 mol) was added dropwise to the reaction mixture at 40° C. The reaction mixture was heated at 100 to 110° C. for 12 hours to give a thick solution. The reaction mixture was then cooled to room temperature. The mixture was added to 250 mL methanol to give a grey precipitate. The precipitated resin was filtered, vacuum dried at 60 to 70° C. to give 3.6 g resin (Sample 3) as grey powder. Analysis by GPC: M_(w)=2697, PDI=1.6.

EXAMPLE 4

The procedure of Example 1 was generally repeated except that the solvents and acids shown in Table 1 were used.

TABLE 1 Sample Solvent Acid M_(w) PDI 4-1 PGMEA CH₃SO₃H 5012 2.2 4-2 GBL CH₃SO₃H 2910 1.53

EXAMPLE 5

The procedure of Example 1 is repeated except that 2-naphthaldehyde was replaced with the aldehydes listed in Table 2.

TABLE 2 Sam- ple Aldehyde Solvent Acid 5-1  Anthracene-2-carbaldehyde GBL CH₃SO₃H 5-2  Pyrene-1-carbaldehyde EtOH/PGME HCl 5-3  6-Hydroxyanthracene-6- EtOH/PGME H₂SO₄ carbaldehyde 5-4  Phenanthrene-2-carbaldehyde GBL CH₃SO₃H 5-5  6-Hydroxy-2-naphthaldehyde EtOH/PGME HCl 5-6  5-Hydroxy-2-naphthaldehyde EtOH/PGME HCl 5-7  6-Hydroxypyrene-1- EtOH/PGME HCl carbaldehyde 5-8  Triphenylene-2-carbaldehyde GBL CH₃SO₃H 5-9  5-Hydroxyanthracene-6- EtOH/PGME H₂SO₄ carbaldehyde 5-10 Anthracene-9-carbaldehyde GBL CH₃SO₃H 5-11 3-Hydroxyanthracene-9- EtOH/PGME HCl carbaldehyde 5-12 2-Hydroxy-3-naphthaldehyde EtOH/PGME Propionic acid 5-12 2-Methoxy-1-naphthaldehyde GBL CH₃SO₃H 5-13 2-Benzyloxy-1- GBL CH₃SO₃H naphthaldehyde 5-14 9-Phenylanthracene-2- GBL CH₃SO₃H carbaldehyde 5-15 9-Hydroxytriphenylene-2- EtOH/PGME H₂SO₄ carbaldehyde 5-16 5-Phenyl-2-naphthaldehyde GBL CH₃SO₃H 5-17 5-Phenyl-2-naphthaldehyde 4-methylanisole pTSA

EXAMPLE 6

A three-necked 50 mL round-bottom flask was equipped with a mechanical stirrer, a thermowell, and a condenser with a nitrogen inlet. The flask was charged with 1-pyrenol (10.0 g, 0.0458 mol), 2-naphthaldehyde (7.156 g, 0.0458 mol), and PGME (40 mL). Stirring was then initiated and the reaction mixture was stirred at room temperature under nitrogen. A clear solution was obtained after 30 minutes. Methanesulfonic acid (2.201 g, 0.0229 mol) was added to the reaction mixture. The reaction mixture was heated at 120° C. for 4 hours to give a thick solution. The reaction mixture was then cooled to room temperature. The mixture was added to 400 mL methanol and water (v/v=4:1) to give a grey precipitate. The precipitated resin was filtered, vacuum dried at 60 to 70° C. to give 11.3 g resin as grey powder (Sample 6). Analysis by GPC: M_(w)=1229, PDI=1.2.

EXAMPLE 7

The procedure of Example 6 was repeated except that the 1-pyrenol loading and reaction times used were as shown in Table 3.

TABLE 3 Sample 1-Pyrenol Time M_(w) PDI 7-1 1.5 equivalents 11 hr. 1150 1.15 7-2  2 equivalents 11 hr. 1000 1.13

Comparative Example 1

A three-necked 50 mL round-bottom flask was equipped with a mechanical stirrer, a thermowell, and a condenser with a nitrogen inlet. The flask was charged with 1-pyrenol (5.0 g, 0.0229 mol), benzaldehyde (2.431 g, 0.0229 mol), PGME (10 mL) and EtOH (7 mL). Stirring was then initiated and the reaction mixture was heated to 60° C. under nitrogen. A clear solution was obtained after 30 minutes and heating was removed at that time. HCl (3.0 mL, 37% aqueous) was added dropwise to the reaction mixture at 40° C. The reaction mixture was refluxed for 24 hours to give a thick, dark brown solution. The reaction mixture was cooled to room temperature and diluted with 10 mL PGME. The mixture was then added to 500 mL methanol to give a light grey precipitate. The precipitated resin was filtered, vacuum dried at 60 to 70° C. to give 1.0 g resin (Comparative 1) as grey powder. Analysis by GPC: M_(w)=4526, PDI=1.88.

Comparative Example 2

A sample (Comparative 2) of a polymer having the repeating unit shown in formula (V) was obtained from Gun Ei Chemical, and used as is. The molecular weight of this sample was: M_(w)=6066, and M_(n)=2362.

EXAMPLE 8

The aromatic resin reaction products listed in Table 5 were individually formulated in propyleneglycol monomethylether acetate (PGMEA) or cyclohexanone at 10 wt % solids, filtered through 0.2 μm poly(tetrafluoroethylene) (PTFE) syringe filter, coated on a silicon wafer at 1500 rpm and baked at 100° C. for 60 seconds to remove the solvent, and further cured at 400° C. for 60 seconds. The cured films were etched using either O₂ or CF₄ plasma using a Plasmatherm RIE790 tool (from Plasma-Therm Co.) and the conditions shown in Table 4. The etching data, in A/sec., are reported in Table 5.

TABLE 4 Gas O₂ CF₄ Flow (sccm) 60 50 Power (W) 700 500 Pressure (mTorr) 10 10 Etch time (sec.) 30 60

TABLE 5 Sample O₂ Etch - Å/sec. CF₄ Etch - Å/sec. 2 23.5 3.0 4-1 26.4 3.2 4-2 27.2 5.6 6 23.2 5.1 7-1 22.4 3.7 7-2 21.9 2.6 Comparative 1 28.2 4.1 Comparative 2 31.6 5.0 

What is claimed is:
 1. A reaction product formed from a combination comprising one or more first monomers of the formula

wherein Y is selected from H, C₁-C₃₀alkyl, C₂-C₃₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —C₁-C₃₀alkylene-OR¹, and —C₁-C₃₀alkylidene-OR¹; each R is independently selected from C₁-C₃₀alkyl, C₂-C₃₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —OR¹, —C₁-C₃₀alkylene-OR¹, and —C₁-C₃₀alkylidene-OR¹; R¹ is selected from H, C₁-C₃₀alkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, and C₇-C₃₀aralkyl; and n is an integer selected from 0 to 7; and one or more second monomers of the formula Ar—CHO, where Ar is a C₁₀-C₃₀aromatic moiety having at least 2 fused aromatic rings, which may optionally be substituted with one or more of C₁-C₃₀alkyl, C₂-C₃₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —OR³, —C₁-C₃₀alkylene-OR³ and —C₁-C₃₀alkylidene-OR³; R³ is selected from H, C₁-C₃₀alkyl, and C₆-C₃₀aryl.
 2. The reaction product of claim 1 wherein n=0 to
 4. 3. The reaction product of claim 1 wherein each R is independently selected from C₁-C₂₀alkyl, C₂-C₂₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —OR¹, —C₁-C₁₂alkylene-OR¹, and —C₁-C₂₀alkylidene-OR¹.
 4. The reaction product of claim 1 wherein second monomer is substituted with one or more hydroxyls.
 5. The reaction product of claim 1 wherein Ar is a C₁₀-C₃₀aromatic moiety having 2 to 5 fused aromatic rings.
 6. A process for preparing a reaction product comprising reacting one or more first monomers of the formula

wherein Y is selected from H, C₁-C₃₀alkyl, C₂-C₃₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —C₁-C₃₀alkylene-OR¹, and —C₁-C₃₀alkylidene-OR¹; each R is independently selected from C₁-C₃₀alkyl, C₂-C₃₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —OR¹, —C₁-C₃₀alkylene-OR¹, and —C₁-C₃₀alkylidene-OR¹; R¹ is selected from H, C₁-C₃₀alkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, and C₇-C₃₀aralkyl; and n is an integer selected from 0 to 7; with one or more second monomers of the formula Ar—CHO, where Ar is a C₁₀-C₃₀aromatic moiety having at least 2 fused aromatic rings, which may optionally be substituted with one or more of C₁-C₃₀alkyl, C₂-C₃₀alkenyl, C₇-C₃₀aralkyl, C₆-C₃₀aryl, substituted C₆-C₃₀aryl, —OR³, —C₁-C₃₀alkylene-OR³ and —C₁-C₃₀alkylidene-OR³; R³ is selected from H, C₁-C₃₀alkyl, and C₆-C₃₀aryl in the presence of an acid, and optionally in a solvent.
 7. The process of claim 6 wherein the solvent is polar.
 8. The process of claim 6 wherein the acid is selected from dicarboxylic acids, mineral acids and sulfonic acids.
 9. A polymeric reaction product produced by the process of claim
 6. 10. A composition comprising the reaction product of claim 1, organic solvent, and optionally one or more additives chosen from curing agents, crosslinking agents, and surfactants.
 11. A process of forming a patterned layer comprising disposing a layer of the composition of claim 11 on a substrate; removing organic solvent to form a reaction product layer; disposing a layer of a photoresist on the reaction product layer; exposing the photoresist layer to actinic radiation through a mask; developing the exposed photoresist layer to form a resist pattern; and transferring the pattern to the reaction product layer to expose portions of the substrate.
 12. The process of claim 11 further comprising the steps of patterning the substrate; and then removing the patterned reaction product layer.
 13. The process of claim 11 further comprising the steps of disposing a conformal silicon-containing layer over the patterned reaction product layer and exposed portions of the substrate; partially etching the silicon-containing layer to expose a top surface of the patterned polymeric reaction product layer and a portion of the substrate. 